GB1411520A - Circuit arrangements for the production of two signals hilbert- transformed relative to one another - Google Patents

Abstract

1411520 Active filters; amplitude modulators SIEMENS AG 21 June 1973 [22 June 1972] 29459/73 Headings H3U and H3R An arrangement for producing at outputs E, G two signals Hilbert-transformed relative to each other, comprises two digital filters 25, 26, of which the coefficient element arrangements 37, 37b are identical and are arranged to produce relative phase shifts of + 45 and - 45 degrees respectively, and wherein arrangements 37, 37b are connected to the delay elements 4, 5 in reverse sequence respectively relative to the direction of transmission of an input signal applied at 18. In a first modification, Fig. 10 (not shown) a single group of delay elements, common to both filters, is used. In a second modification Fig. 11 (not shown) for multi-state input signals, further units are provided, the outputs being combined by further coefficient elements and adders. The arrangement may be employed in a single sideband modulator, Fig. 12. An input signal to be modulated is applied at A to the two digital filters 25, 26 to produce at 30, 31 two signals which are Hilbert-transformed relative to each other. These are then fed via L.P. filters 23, 24 to amplitude modulators 81, 82 which are fed with quadrature carrier signals by means of carrier oscillator 83 and 90 degree phase shifter 84.